Placental previa in relation to induced and spontaneous abortion: a population-based study.

ABSTRACT

OBJECTIVE: To evaluate the impact of induced abortion and spontaneous abortion on the occurrence of placenta previa in later pregnancies. METHODS: A population-based, case-control study was conducted using 1984-1987 Washington state birth certificate data. The study population included 486 white women with a pregnancy complicated by placenta previa and 1598 randomly selected controls without placenta previa. Unconditional logistic regression was used to estimate odds ratios and 95% confidence intervals (CIs). RESULTS: After adjustment for confounding variables, the odds ratio in association with one or more induced abortions was 1.28 (95% CI 1.00-1.63). For one or more spontaneous abortions, the odds ratio was 1.30 (95% CI 1.01-1.66). CONCLUSIONS: Women who report one or more induced or spontaneous abortions are 30% more likely to have a subsequent pregnancy complicated by placenta previa than women without such a history. The results should not be generalized to areas where suction curettage is not the preferred method of induced abortion.